1. Field of the Invention
The present invention relates to a device for storing and a controlled delivery of a pressurized product and including a substantially dimensionally stable outer container, a flexible inner container for storing the pressurized product and located in the outer container, a pressurized liquid or gaseous motive medium located in an intermediate space between the outer container and the inner container, and a valve for connecting the outer and inner containers and having a housing for connecting the outer and inner containers, a piston, and a sealing region.
2. Description of the Prior Art
European publication EP 0 320 510B1 discloses a device for storing and a controlled delivery of a pressurized product and including a substantially dimensionally stable outer container, a flexible inner container for storing the pressurized product and located in the outer container, a pressurized liquid or gaseous motive medium located in an intermediate space between the outer container and the inner container, and a valve for connecting the outer and inner containers.
Because the valve can be welded to the inner container, the inner layer of the inner container and the valve housing are formed of an easy weldable material. As a rule, polyethylene (PE) or polypropylene (PP) are used. However, these materials are not sufficiently diffusion-proof. Therefore, the motive means, gas or liquid, can intermix with the product stored in the inner container as a result of a diffusion process. This causes a pressure drop in the motive medium and contamination of the stored product.
Accordingly, an object of the present invention is to provide a device for storing and a controlled delivery of a pressurized product in which intermixing of the product, which is stored in the inner container, with the motive gas or liquid, which is located in the intermediate space between the outer and inner containers, is reliably prevented.
This and other objects of the present invention, which will become apparent hereinafter, are achieved by providing a device for storing and a controlled delivery of a pressurized product in which the inner container is formed of a foil of a diffusion-proof material, and the valve sealing region is arranged in the interior of the inner container.
The arrangement of the valve sealing region in the inner container and forming the inner container of a diffusion-proof material prevent intermixing of the pressurized product with the motive gas or liquid. The motive medium, which diffuses through the valve housing, is expelled from the device through the opening in the outer container.
In order to prevent the product from leaving the inner container when the valve is in its non-actuated position, preferably the valve piston is biased against a stop surface provided on the valve housing by a spring, with the valve sealing ring being arranged between the valve piston and the stop surface.
According to the present invention, a valve spool, which is formed integrally with the valve piston, projects from the piston in the product delivery direction and has a side opening located in the region of the valve sealing ring and opening into a central outlet channel formed in the spool. The outlet opening of the outlet channel of the valve spool is located in the end surface of the spool remote from the valve sealing region. In the valve closed position, the side inlet opening is located outside of the valve sealing region, i.e., outside of the inner container. For moving the valve to its open position, the piston is displaced in a direction opposite the delivery direction against the biasing force of the spring that biases the piston against the stop surface provided on the valve housing. Upon movement of the piston in the direction opposite the delivery direction, the side inlet opening of the spool is located in the interior of the inner container, and the product flows through the side inlet opening and the central outlet channel outside of the device.
Preferably, to provide for a good weldability of the valve housing with the inner container, the foil, of which the inner container is made, is formed of two layers. In addition to the layer of a substantially diffusion-proof material, there is provided a further, inner layer formed of the material weldable with the valve housing.
Advantageously, the foil has, in addition to a layer of a substantially diffusion-proof material, a further, outer layer formed of a material resistant to a mechanical load.
The diffusion-proof material is usually aluminum or an aluminum alloy.
A particularly good weldability of the valve housing with the inner container is achieved when both the inner layer of the inner container and the valve housing are formed of polyethylene (PE) or polypropylene (PP).
The outer layer of the inner container is usually formed of polyamide or polyester.
The novel features of the present invention, which are considered as characteristic for the invention, are set forth in the appended claims. The invention itself, however, both as to its construction and its mode of operation, together with additional advantages and objects thereof, will be best understood from the following detailed description of preferred embodiments, when read with reference to the accompanying drawings.